Plant Diversity and Fire - Fire in Mediterranean Ecosystems - page 311

Table 11.1 Mediterranean-type climate regions and biogeographic characteristics

Mediterranean
Basin

California
Floristic Province Central Chile

Cape Floral
Region

Southwest
Australia

Original primary
vegetation (km 2 )

2 362 000 324 000 300 000 74 000 309 850

Remaining
vegetation (%)

4.7 24.7 30.0 24.3 10.8

Plant species 25 000 4426 3429 8200 5469

Endemics (%) 52 48 47 69 79

Dominant
shrublands

maquis/garrigue chaparral matorral fynbos heath

Fire-dependent
ephemeral flora

none dominant none minor minor

Geophytes moderate moderate moderate very

abundant

very
abundant

Annuals abundant abundant abundant minor minor

Colonization from
outside burn

abundant rare none? none none

Shrubs resprouting most species ∼ half of species most species ∼ half of

species

∼ half of
species

Shrubs with
fire-stimulated
seedling
recruitment

many species in a
few genera

many species in a
few genera

1 or a few
species

many
species,
many
genera

many
species,
many
genera

low in closed-
canopy
shrublands
higher in
open sites

generally
high

generally
high

Prefire diversity low in closed

canopy; high in
disturbed sites

low in closed-
canopy
shrublands;
higher in open
sites

the relative change in vegetation structure after fire. Northern hemisphere MTC
ecosystems largely are dominated by moderately fertile soils and, in the absence of
recent disturbance, often develop closed-canopy shrublands and woodlands (see
Chapters 4 and 5 ). The dominant sclerophyllous-leaved species typically form a
monolayer of tall (2-5 m) evergreen shrubs that shade out most understory
species. Consequently community diversity tends to be rather low, comprising
mostly shrubs and a few vines and lianas. In the understory there may be sparse
populations of a few annual and herbaceous perennial species but these popula-
tions fluctuate with annual precipitation and often disappear under drought
conditions. In the soil, however, there is a rich diversity of long-lived dormant
seeds, bulbs and corms that are triggered to germinate and resprout in response to
fire. As a consequence these communities exhibit dramatic increases in diversity
after fire ( Table 11.2 ).